The present invention relates to white balance processing apparatus and processing method thereof in which pickup images can be readily processed at white balance values of desired color tone, and also relates to a program for executing such processing method and to digital cameras using such white balance processing apparatus.
In imaging apparatus such as a digital camera, white balance adjustment is indispensable in recording taken images. The techniques for such white balance adjustment include an automatic white balance, preset white balance, one-touch white balance, manual white balance, etc.
The most frequently used technique is the automatic white balance (AWB). In this technique, a fetched pickup image is analyzed at the inside of the imaging apparatus to compute an optimal white balance value, and white balance processing is effected on the taken image by using the computed white balance value. Since, however, the white balance adjustment is an adjustment of color condition and involves highly subjective elements, a white balance adjustment based on a theoretically correct white balance value obtained by the automatic white balance technique is not necessarily preferred.
By contrast, there is a technique referred to as preset white balance adjustment. In this technique, the white balance processing is effected by a white balance value which is designated by the photographer from those white balance values previously stored to the imaging apparatus before its shipping from factory, i.e., white balance values corresponding for example to the light sources of fluorescent lamp, incandescent lamp, outdoors, etc.
Further, there is a technique referred to as one-touch white balance adjustment. In this technique, a preliminary image of a white object is taken before the main image taking under the image taking condition to previously set a white balance value, and white balance processing is effected on the pickup image by such set white balance value.
Among other prior-art techniques relating to white balance processing, Japanese patent application laid-open No. 2000-299814 discloses a technique in which the setting of white balance is selected from an automatic setting and a customized setting of the user. Further, Japanese patent application laid-open Hei-10-304386 discloses for example a technique in which an automatic white balance (AWB) function is also locked concurrently with AF and AE functions by the half-pressed manipulation (1st manipulation) of the release switch in taking an image.
Further, Japanese patent application laid-open Hei-11-355784 discloses a digital camera capable of selecting from an automatic white balance adjustment mode and a manual white balance adjustment mode in which the photographer can manually make an adjustment based on a color temperature information.
Furthermore, Japanese patent application laid-open No. 2002-185972 discloses a digital camera in which an achromatic color region is distinguishably displayed on image displayed on an image displaying LCD monitor of digital camera so that a suitable white balance can be set while checking such displayed image.